Fuel injection device



Feb. 5, 1935.

c. G. SPRADO FUEL INJECTION DEVICE Filed Aug. 9, 1926 2 Sheets-Sheet lFeb. 5, 1935- c. G. SPRADO 1,989,891

FUEL INJECTION DEVICE Filed Aug. 9, 1926 2 Sheets-Sheet 2 Patented Feb.5, 1935 UNITED STATES PATENT OFFICE.

FUEL INJECTION DEVICE Application August 9, 1926, Serial No. 128,077

1 Claim.

This invention relates in general to improvements in the constructionand operation of fuel injection devices, and is especially applicable tointernal combustion or oil engines of the direct 5. injection type.

An object of the invention is to provide an improved fuel injectiondevice which is simple in construction and efficient in operation.Another object of the invention is to provide a new and 10 usefulfuelsupply pump for internal combustion or oil engines of the directinjection type. A further object .of the invention is to provide a fuelinjection pump for multi-cylinder oil engines or the like, whereinuniform supply of fluid is 1.3 insured for all of the individualcylinders. These and other objects of the invention will appear from thefollowing description.

A clear conception of several embodiments of the invention and of themode of operating fuel 20 injection devices constructed in accordancetherewith, may be had by referring to the drawings accompanying andforming a part of this specification in which like reference charactersdesignate the same or similar parts in the vari- 25 ous views.

Fig. 1 is a central vertical section through one form'of the improvedfuel injection device and through the actuating mechanism therefor.

Fig. 2 is a longitudinal sectional view through another form of theimproved fuel injection device especially applicable to multi-cylinderengines.

Fig. 3 is a transverse sectional view through the fuel injection deviceof Fig. 2, showing a 3 regulator diagrammatically associated therewith.Fig. 4 is a top view of the fuel injection device disclosed in Figs. 2and 3. I

Referring specifically to the embodiment of the invention illustrated inFig. 1, the fuel injec- 0 tion device comprises in general a stationarycasing forming a displacement chamber 2; a movable member or plunger 4having an end face constantly exposed to the displacement chamber 2; areciprocable piston 3 for introducing liquid 5 such asfuel oil, into thechamber 2; an inlet valve 6 operable by the movement of the piston 3 topermit the flow of liquid into the chamber 2; a discharge valve 5 forcontrolling the delivery of liquid from the chamber 2; mechanism for Jactuating the piston 3; and means for varying the pressure tending tourge the plunger 4 toward the chamber 2. The instrumentalities forvarying the pressure tending to urge the plunger 4 toward the chamber 2,consist of a pressure 5 chamber 12 having an adjusting piston 13 exposedthereto, and adapted to receive a supply of compressible fluid underpressure past-the adjustable regulating-valve 14. The plunger 4 isconstantly urged away. from the displacement chamber 2 by means of acompression spring 11, 5 this spring opposing the pressure acting uponthe piston 13 within the chamber 12. The liquid supply piston 3 isreciprocable with respect to the displacement chamber 2 by means of anactuating arm 15 having a roller 18 thereon 00- acting with an actuatingcam 'or eccentric 16 associated with a constantly rotating shaft 1'7.The piston 3 is urged away from the displacement chamber 2 by means of acompression spring 10, this spring at all times maintaining the roller18 in engagement with the peripheral surface of the eccentric 16.The-inlet valve 6 is normally spring pressed against its seating to cutoff the flow of fluid from a supply pipe 8 to the displacement chamber2. An unloading 20 rod 9 cooperates with the inlet valve 6 to maintainthis valve open during a predetermined portion' of the pressure strokeof the piston 3, under certain conditions of operation. The unloadingrod 9 is connected to one end of a lever 19, the opposite end of whichis connected to the arm 15 by a connection 22, and the medial portion ofwhich is fulcrumed upon an eccentric 20. The eccentric 20 is adjustablein position by means of regulating mechanism such as a governor,associated with the connection 21. The discharge valve 5 is formed tocontrol the delivery of liquid from the displacement chamber 2 to thedis charge line 7, the valve 5 being normally spring pressed against-itsseating. The discharge line 7 may have a second fuel injection valve ofusual form therein, for controlling the delivery of liquid to a sourceof utilization such as a cylinder of an oil engine.

Referring specifically to the embodiment of the 0 invention illustratedin Figs. 2, 3 and 4, which embodiment is especially applicable tomulti-cylinder engines or the like, the fuel injection device comprises,a fuel supply chamber 23 communicating with a common displacementchamber 27formed within a suitable stationary casing, the chambers 23,27 being connected by passages or conduits 41 each having a dischargevalve 40 therein; a common member or plunger 26 constantly movabletoward and away from the displacement chamher 27 to establish apredetermined pressure therein; and a series of reciprocable pistons 28for introducing definite quantities of liquid into .the displacementchamber 27 from the supply chamber 23 through the passages 41. Thechamher 23 has a supply line 24 communicating therewith, and is alsoprovided with a vent passage 44 for permitting the escape of air. Thedisplacement chamber 27 communicates with a discharge line 25 whichnormally conducts the fuel oil to the injection devices or valves at theengine, these valves being of well known construction and being formedto permit delivery of oil from the discharge line 25 to each cylinder atpredetermined intervals. The plunger 26 is constantly urged toward thechamber 2'7 by means of a compression spring 38 the tension of which isvariable by means of an adjusting screw 39. Each of the pistons 28 isprovided with a compression spring 37 for urging the piston away fromthe adjacent conduit 41, against an actuating eccentric 30. Theactuating eccentrics are carried by a common shaft which is supported atthe medial portions of a pair of adjusting arms 31, the correspondingends of which are secured to a common pivot shaft 42, and the oppositecorresponding ends of which are associated with a cross-rod 32. Theeccentrics 30 are constantly rotatable by means of gearing 33 and anactuating shaft 34 which is driven by the engine. The cross-rod 32 isconnected to a governor 36 or other means-for varying the position ofthe arms 31 with respect to the pivot 42, by means of connections 35.Each of the discharge valves 40 is spring pressed toward its seating andis accessible by virtue of a removable cap 43 associated with the maincasing of the injection device.

During normal operation. of the injection device illustrated in Fig. 1,the shaft 17 is being rotated thereby causing the eccentric 16 toreciprocate the piston 3 through the roller18 and the arm 15. As thepiston 3 is withdrawn from the displacement chamber 2, the dischargevalve 5 remains closed and the inlet valve 6 is opened by the suctiondue to the withdrawal movement of the piston to admit a full quantity ofliquid to the chamber 2 from the supply line 8. 'If the unloading rod iswithdrawn so as not to engage the valve 6, then this valve will engageits seating when the piston 3 has reached its lowermost position andwill remain seated during the entire upward stroke of the piston 3. Ifthe injection valve at the engine is open, when the piston 3 movesupwardly, liquid is discharged from the displacement chamber 2 past thevalve 5 by the action of the plunger 4. If the injection valve is closedwhen the piston 3 moves upwardly, then the oil in the chamber 2 merelycauses the plunger 4 to move away from this chamber. The moment theinjection valve of the engine is open, the plunger 4 immediately becomeseffective to urge oil through the discharge line 7 to the engine at apredetermined constant pressure and independently of the motion of thepiston 3. If the pressure in the chamber 12 is varied, the plunger 4will assume a new position in accordance with such variation of thepressure in the chamber 12. When the rod 9 is adjusted to engage theinlet valve 6 during a portion of the upward stroke of the piston 3,some of the oil within the displacement chamber 2 is returned to thesupply line 8, and such return of liquid is immediately stopped when therod 9 is withdrawn from the valve 6,. By varying the timing of theeccentric 16 the timing of the reciprocation of the piston 3 is alsovaried, anu such variation in the time of movement of the eccentric 16,is a well known expedient in the art. v

During normal operation of the modified fuel injection device disclosedin Figs. 2, 3 and 4, the

eccentrics 30 are being constantly rotated to reciprocate the pistons28.. Due to the angular position of the eccentrics 30, the pistons 28act successively to urge oil from the supply chamber 23 through thedisplacement conduits 41 and past the valves 40 to the commondisplacement chamber27. The plunger 26' is constantly movable toward andaway from the displacement chamber 27 due to variation in the quantityof oil being delivered to the chamber 2'7 by the pistons 28 and also dueto the successive opening of the fuel injection valves. The spring 38however acts to maintain a constant pressure within the displacementchamber 27 regardless of the quantity of oil being supplied .by thepistons or the quantity of oil discharged, and this constant pressuremay be conveniently varied by adjusting the set,

screw 39. As the pistons 28 supply oil to the chamber 27, the plunger 26recedes from this chamber, and as the injection valves at the en- --gineare opened to admit fuel to the cylinders,

the plunger 26 becomes effective to urge the oil through these injectionvalves. The governor 36 Y operates to automatically adjust the arms 31to vary the effective strokes of the piston 28 in an obvious manner, andthe discharge valves 40 merely serve as check valves for preventing re-.turn of oil from the chamber 27 to the chamber 23.

From the foregoing description it will be apparent that the constantlymovable plunger .serves to deliver oil at a predetermined pressureinsures an abundant supply of fuel at the desired pressure regardless ofthe number of cylinders embodied in the engine to which the device isapplied. i

It should be understood that it is not desired to limit the invention tothe exact details of construction and operation herein shownand de-.scribed, for various modifications within the scope of the claim mayoccur to persons vskilled in the art.

It is claimed and desired to secure by Letters Patent:

A fuel injection pump for an internal combustion engine, comprising acasing forming a displacement chamber and a plurality of cylinders, aplurality of pistons disposed to reciprocate within said cylinders todisplace fuel from said cham- Y her, a shaft having a plurality ofeccentrics adapted respectively to engage the ends of said pistons, apair of arms pivotally mounted on said casing and positioned torotatably support said eccentric shaft in position to actuate saidpistons, means for drivingsaid eccentric shaft including a rigidlymounted driving worm meshing with agear wheel on said eccentric shaft,and means responsive to changes in the speed of the engine for pivotingsaid arms to move said eccentric shaft relative to said casing andlongitudinally CARL G. SPRADO.

